TODO this is less efficient on python2

flake8 --select E713, semi-manual fixing

python modernize.py --no-six -f libmodernize.fixes.fix_print -w

With manual fixes as the import was put always on top.

refs #803

autopep8 -i --select=W602
Also some other minor deprecated syntax changes, like "while 1".
I did not commit the less obvious changes.

This is recommended by Debian.
closes #618